Uptake of Pb by Human Skeleton and Comparative Metabolism of Pb and Alkaline Earth Elements

Abstract

Measurements of the retention of 47Ca and of 203Pb were made following their administration by intravenous injection. Translocation to bone was measured by gamma counting the feet of subjects. Uptake by bone of 203Pb was comparatively slow and extrapolation to the whole skeleton indicated that 20% of the dose had been taken up within 20 days. By time, a similar fraction of the dose had been excreted in urine. These results are consistent with Kehoe's (Ke61) long-term balance studies on 2 human subjects given stable Pb orally. Uptake by bone of 47Ca was about 1.5-2 times the amount excreted in urine. Both the uptake by bone, and its excretion in urine, were more rapid than that of 203Pb due to the greater attachment of the latter to red blood cells. However, the plasma clearance rate for Pb, like that of Sr, was greater than that of Ca.

Pb distribution in bones from the Franklin expedition: synchrotron X-ray fluorescence and laser ablation/mass spectroscopy

“…The second statement is consistent with the existing literature on the mechanism and kinetics of bone Pb/bone blood exchange [16][17][18][19][20][21][22][23]. The long half-life of Pb in bone is especially relevant to an understanding of the Pb content of the Beechey Island burials, which occurred early in the expedition.…”

“…Individual metals are displayed using a color scale based on the maximum concentration of the metal; the scale is not normalized in such a way as to allow direct comparison of the concentrations of different metals. While it has been suggested that a detailed study of the Haversion canals in bone may provide a chronology of Pb accumulation [36], the existing literature [16][17][18][19][20][21][22][23] on the kinetics of Pb/bone exchange make it clear that the Pb distribution patterns within bone will provide a realistic chronology of uptake. The significance of the distribution of other metals must be uncertain, though the Beechey Island materials (Fig.…”

“…Modern Pb values vary widely but concentrations in the order of 3 to 30 ppm might be expected [21]. The levels reported in remains from the Franklin expedition are consistent with neurological effects which may have contributed to the failure of the mission [9,22,23]. However, anomalously high Pb was not uncommon in the eighteenth and nineteenth centuries [24][25][26][27].…”

Dietary lead intakes for mother/child pairs and relevance to pharmacokinetic models.

“…In the EPA Integrated Exposure Uptake Biokinetic (IEUBK) model (9), the higher absorption values among adult males are applied to children up to 7 years old. The adult values for gastrointestinal lead uptake are fairly well validated using long-term mass balance studies (12,13), radioactive tracers (14)(15)(16)(17)(18)(19), and stable isotope tracers (20,21). Most adult subjects were males.…”

Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study

“…Data for laboratory animals indicate that fractional deposition on bone surfaces, as judged by the total skeletal content in the first few hours after injection, is similar for calcium, strontium, barium, and radium, despite the different excretion rates of these elements (Bligh and Taylor 1963;Kshirsagar et al 1966;Domanski et al 1969Domanski et al , 1980. Use of a common bone-surface deposition fraction for all four elements is also consistent with the limited human data, including: autoradiographic measurements of surface activity in bone samples taken at autopsy from subjects injected with radiocalcium at 0.6 d or longer before death (Riggs et al 1971, ICRP 1973; calcium and strontium concentrations in autopsy samples of bone from subjects injected with radiocalcium and radiostrontium at 3 h or longer before death (Schulert et al 1959); externally measured buildup and decline of injected radiocalcium over areas of the human body where bone activity is expected to predominate (Anderson et al 1970, Heard andChamberlain 1984); and external measurements of the peak skeletal content of intravenously injected 133m Ba in human subjects (Korsunskii et al 1981). Based on these data, it is assumed that 25% of calcium, strontium, barium, or radium leaving plasma is deposited on bone surfaces of the mature adult.…”